The present invention relates generally to medical devices and particularly to containers and methods for storing and delivering expandable heart valve prostheses especially for use in minimally-invasive surgeries.
Prosthetic heart valves are used to replace damaged or diseased heart valves. In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers: the left and right atria and the left and right ventricles, each provided with its own one-way valve. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid and pulmonary valves. Prosthetic heart valves can be used to replace any of these naturally occurring valves.
Where replacement of a heart valve is indicated, the dysfunctional valve is typically cut out and replaced with either a mechanical valve or a tissue valve. Tissue valves are often preferred over mechanical valves because they typically do not require long-term treatment with anticoagulants. The most common tissue valves are constructed with whole porcine (pig) valves, or with separate leaflets cut from bovine (cow) pericardium. Although so-called stentless valves, comprising a section of porcine aorta along with the valve, are available, the most widely used valves include some form of stent or synthetic leaflet support. Typically, a wireform having alternating arcuate cusps and upstanding commissures supports the leaflets within the valve, in combination with an annular stent and a sewing ring. The alternating cusps and commissures mimic the natural contour of leaflet attachment.
A conventional heart valve replacement surgery involves accessing the heart in the patient""s thoracic cavity through a longitudinal incision in the chest. For example, a median sternotomy requires cutting through the sternum and forcing the two opposing halves of the rib cage to be spread apart, allowing access to the thoracic cavity and heart within. The patient is then placed on cardiopulmonary bypass which involves stopping the heart to permit access to the internal chambers. Such open heart surgery is particularly invasive and involves a lengthy and difficult recovery period.
Recently, a great amount of research has been done to reduce the trauma and risk associated with conventional open heart valve replacement surgery. In particular, the field of minimally invasive surgery (MIS) has exploded since the early to mid-1990s, with devices now being available to enable valve replacements without opening the chest cavity. MIS heart valve replacement surgery still typically requires bypass, but the excision of the native valve and implantation of the prosthetic valve are accomplished via elongated tubes (catheters or cannulas), with the help of endoscopes and other such visualization techniques. Some examples of recent MIS heart valves are shown in U.S. Pat. No. 5,411,552 to Anderson, et al., U.S. Pat. No. 5,980,570 to Simpson, U.S. Pat. No. 5,984,959 to Robertson, et al., PCT Publication No. 00/047139 to Garrison, et al., and PCT Publication No. WO 99/334142 to Vesely.
To minimize the possibility of damage to the relatively delicate tissue type or bioprosthetic heart valves, they are packaged in jars filled with preserving solution for shipping and storage prior to use in the operating theater. In doing so, the valves are stabilized to prevent the valves from striking the inside of the jar. Prior to implantation in a patient, residual traces of the preserving solution need to be washed from the valve. This washing is accomplished by first removing the valve from the jar and then rinsing the valve in a shower. Alternatively, the valve may be immersed and agitated in a bath. Typically, the medical technician removes the valve from its jar by grasping a valve holder with a gloved hand. The valve holder is typically centrally located with respect to, and sutured to, the valve sewing ring. A surgical handle is then threaded into a socket provided in the valve holder. The valve is then rinsed in the bath or shower while being held at the end of the handle. After rinsing, the handle is used to position the valve in the appropriate implantation site. This conventional process leaves the valve susceptible to damage if the valve strikes a surface while being manipulated on the end of the surgical handle.
Despite some advances in minimally-invasive valve design, there remains a need for a storage and delivery system for such valves that prevents damage to the biological valve, and enables a medical practitioner to easily and safely prepare, remove and rinse the valve.
The present invention provides a storage container for an expandable prosthetic heart valve having both contracted and expanded configurations. In one embodiment, the storage container is sized to receive the heart valve in its expanded configuration, and a mechanism incorporated into the container engages the heart valve and operates to convert the heart valve from its expanded to its contracted configuration. The heart valve may be a tissue-type valve having flexible leaflets and the container holds a solution suitable for preserving the leaflets. The container desirably includes a base and a lid, and the mechanism operable to convert the heart valve from its expanded to its contracted configuration may be partially incorporated into the lid. The base may have a drain to empty the solution from the container. In a preferred embodiment, the mechanism operable to convert the heart valve from its expanded to its contracted configuration is separable from the base such that the heart valve in its contracted configuration may be removed from the base by manipulating the lid.
The heart valve may comprise a generally sheet-like stent body that is spirally-wound about an axis in the contracted configuration and is substantially unwound and at least partly forms a tube centered about the axis in its expanded configuration. The stent body defines a pair of opposed side edges that generally mate in the expanded configuration, and the mechanism includes a key attached to a first side edge, wherein the key rotates to wind the valve from its expanded to its contracted configuration. The mechanism further may include a clamp releasably attached to the container and to a second side edge of the heart valve opposite the first side edge such that the second side edge is held stationary with respect to the container while the key attached to the first side edge rotates. The container desirably includes a base and a lid, wherein the key rotatably couples to the lid and the clamp releasably attaches to the base. The key desirably comprises a shaft passing through the lid and has structure for engaging complementary structure on the first side edge of the heart valve, wherein the storage container further includes a crank rotatably affixed to the shaft and operable from the exterior side of the lid. The clamp preferably comprises a dovetail slide and the base includes a complementary channel for receiving the slide, the dovetail slide further including structure for engaging complementary structure on the second side edge of the heart valve.
In a further aspect, the invention provides a system for storing and delivering an expandable prosthetic heart valve having both contracted and expanded configurations. The system includes a prosthetic heart valve having a generally sheet-like stent body that is spirally-wound about an axis in the contracted configuration and is substantially unwound and at least partly forms a tube centered about the axis in its expanded configuration, the stent body defining a pair of opposed side edges that generally mate in the expanded configuration. In addition, a plurality of flexible, biocompatible membranes incorporated into the stent body form the heart valve leaflets in the second configuration. The system includes a container sized to receive the heart valve in its expanded configuration. A mechanism incorporated into the container winds the heart valve within the container. Preferably, the heart valve is a tissue-type valve and the container holds a solution suitable for preserving the leaflets. Also, the container may include a base and a lid, and the mechanism incorporated into the container for winding the heart valve within the container is partially incorporated into the lid. The base may have a drain to empty the solution from the container.
In a further aspect of the present invention, a method of storing and delivering an expandable prosthetic heart valve having both contracted and expanded configurations is provided. The method comprises providing a prosthetic heart valve having a contracted configuration sized to be delivered to a site of implantation through a catheter and an expanded configuration sized to engage a heart valve annulus. The method further includes storing the heart valve in a container in its expanded configuration, and converting the heart valve from its expanded to its contracted configuration while in the container. Where the heart valve is a rolled-type of valve, the step of converting comprises winding the valve from a relatively large spiral to a relatively tight spiral. The container may include a base and a lid, and a crank rotatably connected to an inner side edge of the valve, and the step of winding comprises turning the crank to wind the inner side edge of the valve. The step of storing preferably includes providing a solution within the container and the method includes draining the solution from the container while the valve remains within the container. The method may further include rinsing the valve after draining the solution from the container and while the valve remains within the container.
A further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.